Switch mode power converters using magnetically coupled galvanically isolated lead frame communication

ABSTRACT

An integrated circuit package for use in a switch mode power converter comprises an encapsulation and a lead frame. A portion of the lead frame is disposed within the encapsulation. The lead frame includes a first conductor having a first conductive loop disposed substantially within the encapsulation. The lead frame also includes a second conductor galvanically isolated from the first conductor. The second conductor includes a second conductive loop disposed substantially within the encapsulation proximate to and magnetically coupled to the first conductive loop to provide a communication link between the first and second conductors. A first control die including a first control circuit is coupled to the first conductor. A second control die including a second control circuit is coupled to the second conductor. One or more control signals are communicated between the first and second control dice through the communication link.

RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No. ______of Balakrishnan et al., filed Nov. 14, 2012, entitled “MagneticallyCoupled Galvanically Isolated Communication Using Lead Frame,” andassigned to the Assignee of the present application.

This application is also related to U.S. patent application Ser. No.______ of Kung et al., filed Nov. 14, 2012, entitled “Noise CancellationFor A Magnetically Coupled Communication Link Utilizing A Lead Frame,”and assigned to the Assignee of the present application.

BACKGROUND INFORMATION

1. Field of the Disclosure

The present invention relates generally to communication betweencircuits that require galvanic isolation. More specifically, examples ofthe present invention are related to communication across an isolationbarrier in switch mode power converters such as power supplies and powerinverters.

2. Background

Switch mode power converters are widely used for household or industrialappliances that require a regulated direct current (dc) source for theiroperation, such as for example battery chargers that are commonly usedin electronic mobile devices. Off-line ac-dc converters convert a lowfrequency (e.g., 50 Hz or 60 Hz) high voltage ac (alternating current)input voltage to a required level of dc output voltage. Various types ofswitch mode power converters are popular because of their well regulatedoutput, high efficiency, and small size along with their safety andprotection features. Popular topologies of switch mode power convertersinclude flyback, forward, boost, buck, half bridge and full bridge,among many others including resonant types.

Safety requirements for isolated switch mode power converters generallyrequire the use of high frequency transformers to provide galvanicisolation between the inputs and outputs of the switch mode powerconverters in addition to the voltage level change at the output.

A major challenge in the market of switch mode power converters isreducing the size and cost of the switch mode power converter whilemaintaining high performance operating specifications. In known isolatedswitch mode power converters, the sensing of the outputs of the switchmode power converters and communication of feedback signals forregulating switch mode power converter output parameters such as currentor voltage is usually accomplished using external isolation componentssuch as, for example, opto-couplers. These known methods add unwantedadditional size as well as cost to switch mode power converters. Inaddition, opto-couplers are slow in operation and in many cases limitthe feedback bandwidth and the transient response of the switch modepower converter.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the present invention aredescribed with reference to the following figures, wherein likereference numerals refer to like parts throughout the various viewsunless otherwise specified.

FIG. 1A shows the conceptual operation of magnetically coupledconductive loops transmitting and receiving signals to communicatedigital or analog information for the purpose of this disclosure

FIG. 1B illustrates another conceptual example of conductive loopssuitable for a bidirectional operation according to teaching of thisdisclosure.

FIG. 2A shows an outside view of one example of an integrated circuitpackage with galvanically isolated magnetically coupled conductive loopsformed by isolated conductors of the lead frame inside the encapsulatedportion of the integrated circuit package in accordance with theteachings of the present invention.

FIG. 2B shows an inside view of one example structure of galvanicallyisolated magnetically coupled conductive loops formed by isolatedconductors of the lead frame inside the example integrated circuitpackage of FIG. 2A in accordance with the teachings of the presentinvention.

FIG. 2C shows an outside view of one example of an integrated circuitpackage with galvanically isolated magnetically coupled conductive loopsformed by isolated conductors of the lead frame inside the encapsulatedportion of the integrated circuit package in accordance with theteachings of the present invention.

FIG. 2D shows an inside view of one example structure of galvanicallyisolated magnetically coupled conductive loops formed by isolatedconductors of the lead frame inside the example integrated circuitpackage of FIG. 2C in accordance with the teachings of the presentinvention.

FIG. 3A shows an outside view of an example of an integrated circuitpackage with a magnetically coupled communication link formed byisolated conductors of the lead frame inside the encapsulated portionthe integrated circuit package in accordance with the teachings of thepresent invention.

FIG. 3B shows an inside view of one example of a lead frame inside anintegrated circuit package with a magnetically coupled communicationlink formed by magnetically coupled conductive loops of isolatedconductors of the lead frame inside the encapsulated portion of theintegrated circuit package in accordance with the teachings of thepresent invention.

FIG. 3C shows an inside view of an example of a lead frame of amulti-die isolated controller integrated circuit package with amagnetically coupled communication link between the controller dice, thelink being formed by magnetically coupled conductive loops of isolatedconductors of the lead frame inside the encapsulated portion of theintegrated circuit package in accordance with the teachings of thepresent invention.

FIG. 3D shows an example side-view of a jumper bond wire coupled to anintegrated circuit die and a conductive loop of an isolated conductor ofa lead frame inside an integrated circuit package in accordance with theteachings of the present invention.

FIG. 4A shows a tilted 3D (3 dimensional) view of an inside view of oneexample of a lead frame of an integrated circuit package with amagnetically coupled communication link formed by magnetically coupledconductive loops of isolated conductors of the lead frame inside theencapsulated portion of the integrated circuit package in accordancewith the teachings of the present invention.

FIG. 4B shows a tilted 3D view of an inside view of one example of alead frame of a multi-die isolated controller integrated circuit packagewith a communication link between the controller dice formed bymagnetically coupled conductive loops formed by isolated conductors ofthe lead frame inside the encapsulated portion of the integrated circuitpackage in accordance with the teachings of the present invention.

FIG. 5 shows a schematic of one example of a synchronous flyback switchmode power converter with secondary control utilizing one example of amulti-die isolated controller integrated circuit package with amagnetically coupled communication link between the controller diceformed by isolated conductors of the lead frame inside the encapsulatedportion of the integrated circuit package in accordance with theteachings of the present invention.

FIG. 6 shows a schematic of one example of a flyback switch mode powerconverter utilizing one example of a multi-die isolated controllerintegrated circuit package including a bidirectional magneticallycoupled communication link between the controller dice inside theencapsulated portion of the integrated circuit package in which outputinformation is transferred to a primary side through the magneticallycoupled communication link and an AC line zero-cross detection signal istransferred to the secondary side through the magnetically coupledcommunication link in accordance with the teachings of the presentinvention.

FIG. 7 shows a schematic of one example of a buck converter utilizingone example of a multi-die isolated controller integrated circuitpackage with a magnetically coupled communication link formed byisolated conductors of the lead frame inside the encapsulated portion ofthe integrated circuit package in accordance with the teachings of thepresent invention.

FIG. 8A shows a schematic of an example of a switch mode power converterincluding one example of a portion of a half-bridge converter utilizingan example of a multi-die isolated controller integrated circuit packagewith a magnetically coupled communication link formed by isolatedconductors of the lead frame inside the encapsulated portion of theintegrated circuit package in accordance with the teachings of thepresent invention.

FIG. 8B shows a schematic of an example of a switch mode power converterincluding another example of a portion of a half-bridge converterutilizing an example of a multi-die isolated controller integratedcircuit package with a magnetically coupled communication link formed byisolated conductors of the lead frame inside the encapsulated portion ofthe integrated circuit package in accordance with the teachings of thepresent invention.

FIG. 8C shows a schematic of an example of a switch mode power converterincluding yet another example of a portion of a half-bridge converterutilizing an example of a multi-die isolated controller integratedcircuit package with a magnetically coupled communication link formed byisolated conductors of the lead frame inside the encapsulated portion ofthe integrated circuit package in accordance with the teachings of thepresent invention.

FIG. 9A shows a schematic of an example of a switch mode power converterincluding one example of a portion of a half-bridge converter utilizingan example magnetically coupled communication link formed by isolatedconductors of the lead frame inside the encapsulated portion of theintegrated circuit package in accordance with the teachings of thepresent invention.

FIG. 9B shows a schematic of an example of a switch mode power converterincluding another example of a portion of a half-bridge converterutilizing an example magnetically coupled communication link formed byisolated conductors of the lead frame inside the encapsulated portion ofthe integrated circuit package in accordance with the teachings of thepresent invention.

Corresponding reference characters indicate corresponding componentsthroughout the several views of the drawings. Skilled artisans willappreciate that elements in the figures are illustrated for simplicityand clarity and have not necessarily been drawn to scale. For example,the dimensions of some of the elements in the figures may be exaggeratedrelative to other elements to help to improve understanding of variousembodiments of the present invention. Also, common but well-understoodelements that are useful or necessary in a commercially feasibleembodiment are often not depicted in order to facilitate a lessobstructed view of these various embodiments of the present invention.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the present invention. Itwill be apparent, however, to one having ordinary skill in the art thatthe specific detail need not be employed to practice the presentinvention. In other instances, well-known materials or methods have notbeen described in detail in order to avoid obscuring the presentinvention.

Reference throughout this specification to “one embodiment”, “anembodiment”, “one example” or “an example” means that a particularfeature, structure or characteristic described in connection with theembodiment or example is included in at least one embodiment of thepresent invention. Thus, appearances of the phrases “in one embodiment”,“in an embodiment”, “one example” or “an example” in various placesthroughout this specification are not necessarily all referring to thesame embodiment or example. Furthermore, the particular features,structures or characteristics may be combined in any suitablecombinations and/or subcombinations in one or more embodiments orexamples. Particular features, structures or characteristics may beincluded in an integrated circuit, an electronic circuit, acombinational logic circuit, or other suitable components that providethe described functionality. In addition, it is appreciated that thefigures provided herewith are for explanation purposes to personsordinarily skilled in the art and that the drawings are not necessarilydrawn to scale.

In some applications multiple controllers may be housed in a singleintegrated circuit package. Each controller is fabricated as asemiconductor die. The present application discloses an integratedcircuit package structure that enables communication between thecontrollers with galvanic isolation using magnetic coupling betweenportions of the lead frame while adding little or no cost to the overallpackage.

An integrated circuit package typically includes a lead frame. The leadframe provides mechanical support for a single die or for multiple dicethat may be housed within the integrated circuit package. In general,the lead frame typically includes a die attach pad to which asemiconductor die may be attached. In addition, the lead frame generallyalso includes leads that serve as electrical connections to circuitsexternal to the integrated circuit package. The lead frame is generallyconstructed from a flat sheet of metal. The flat sheet of metal may bestamped, etched, punched, etc., with a pattern, which defines the dieattach pads and various leads of the lead frame.

As mentioned above, isolation is often provided in known switch modepower converters using external isolation components such as for exampleopto-couplers or through the use of an extra bias (e.g., feedback)winding on the transformer core that is magnetically coupled to thesecondary winding. These known methods add unwanted additional size aswell as overall cost to switch mode power converters. Isolation isprovided in examples in accordance with the teachings of the presentinvention with magnetically coupled conductive loops formed bygalvanically isolated conductors of the lead frame inside theencapsulated portion of an integrated circuit package structure, whichprovides a magnetically coupled communication link between isolatedcircuits. In various examples, the isolation provided by themagnetically coupled communication link formed by isolated conductors ofthe lead frame of the integrated circuit package in accordance with theteachings of the present invention may be utilized in a variety ofapplications including switch mode power converters that requiregalvanic isolation between the primary and secondary sides of the switchmode power converters. Some example switch mode power convertersutilizing an integrated circuit package having a magnetically coupledcommunication link formed by isolated conductors of the lead frame ofthe integrated circuit package include, but are not limited to,synchronous flyback, isolated flyback, isolated synchronous flyback,buck, forward, half-bridge and full-bridge topologies in accordance withthe teachings of the present invention.

For the purpose of this disclosure, a physical closed path for currentis referred to as a loop. A loop may include different elements such asconductors (that in examples of this disclosure could be formed by leadframe and bond wires inside an IC package) as well as electricalcomponents that are in path of the circulating current. Each element inthe loop forms a part of the loop, and combination of one or moreelements in the loop is referred to as a partial loop. In the context ofmagnetic field coupling, a loop enclosing a magnetic field is typicallyreferred to as having one or more turns. Each turn corresponds to oneenclosure of the magnetic field.

FIGS. 1A and 1B show the conceptual operation of magnetically coupledconductive loops transmitting and receiving signals to communicateoperational information for example in a controller IC of a switch modepower converter in accordance with the teachings of the presentinvention. In FIG. 1A the magnetically coupled communication link 100includes an outer conductive loop 102 coupled to a transmit circuit 110and an inner conductive loop 105 coupled to a receive circuit 130. Theouter conductive loop 102 in one example includes a pulse current source114, injecting a pulse current 120 to conductive loop 102. Inembodiments, the transmit circuit 110 may communicate informationutilizing the transmitter current I_(T) 120. In one example, circuitswithin transmit circuit 110 may control various properties of thetransmitter current I_(T) 120 to communicate information to the receivecircuit 130. When the transmitter current I_(T) 120 is changing orvarying in magnitude over time, it produces a changing magnetic field inthe proximity of the conductor of the inner conductive loop 105. Due tothe laws of electromagnetic induction, a voltage is generated across aconductor that is subjected to a changing magnetic field. The pulsecurrent I_(T) 120 in one example has a time when it is rising, a timewhen it is falling and an amplitude. The changing flux generated byouter conductive loop 102 due to transmitter current I_(T) 120 has adirection entering the surface of the page. Marker 108 illustrates theoverall magnetic field that passes through both transmitter loop 102 andreceiver loop 105. In general, the “X” symbol as illustrated for marker108 denotes magnetic field or flux into the page, while a dot symbol fora marker symbol denotes magnetic field or flux out from the page.

In the embodiment therefore, receiver voltage V_(R) 140 is induced dueto the changing magnetic field generated by changes in current I_(T) 120and may result in receiver current I_(R) 138 in the directionillustrated in FIG. 1A.

The receive circuit 130 may include circuits which may receive thevoltage and/or current induced by the transmit circuit 110 andinterprets the voltage and/or current as information. Properties of thetransmitter current I_(T) 120 which may be controlled to communicateinformation may include the magnitude and rate of change of thetransmitter current I_(T) 120. In the example of depicted transmittercurrent I_(T) 120 the rising and falling slopes defined by the pulsewaveform 120 induce pulsating voltage V_(R) 140 with a positiveamplitude during rising time and a negative amplitude during fallingtime of the transmitter current pulse waveform 120. The receive circuit130 in one example may include a comparator 132 responding to acomparison of the amplitude of induced voltage pulses V_(R) 140 ofreceive circuit 130 to a threshold voltage V_(Th) 134.

The communicated signals may take the form of digital information or ofanalog information. In the case of digital information, communicationcan be in the form of binary signals or more complex encoded digitaldata as will be known to one skilled in the art It is appreciated thatother communication techniques may be used. In other examples,communication techniques which take advantage of the relationshipbetween the transmitter current I_(T) 120 and the resultant inducedreceiver voltage V_(R) 140 and receiver current I_(R) 138 received bythe receive circuit 130 may be utilized.

FIG. 1B illustrates another example of the magnetically coupledcommunication link 150. In one example communication link 150 could besuited for bidirectional communication and includes two conductiveloops. First loop 152 and second loop 155 are positioned to enclose themaximum common magnetic field area. In contrast to the example of FIG.1A, that could be better suited to a unidirectional communication, loops152 and 154 of bidirectional example of FIG. 1B have approximately thesame dimensions. For the best bidirectional operation, physical symmetryof the loops is important resulting in approximately equal bidirectionalbehavior. The magnetic field or flux in the first loop 152 and secondloop 155 has a direction into the page.

The operational/functional difference between FIG. 1A and FIG. 1B isthat in FIG. 1B both first loop 152 and second loop 155 are coupled tothe transceiver (transmit/receive) circuits 160 and 180 respectively.Transceiver circuit 1, 160 through the selection switch S1 163 maycouple either a transmit circuit 162 or receive circuit 165 to the firstloop 152

Transceiver circuit 2, 180 through the selection switch S2 183 maycouple either a transmit circuit 182 or receive circuit 185 to thesecond loop 155

If the Transceiver circuit 1 160 is coupled as a transmit circuit toinject a current pulse I_(TR1) 170 to the first loop, then Transceivercircuit 2 180 through the second loop 155 and switch S2 183 would becoupled as a receive circuit to receive the communicated signal as acurrent pulse I_(TR2) 190 or as a voltage pulse V_(TR2) 187.

On the other hand if the Transceiver circuit 2 180 is coupled as atransmit circuit to inject a current pulse I_(TR2) 190 to the secondloop, then Transceiver circuit 1 160 through the first loop 152 and bythe controlled function of the switch S1 163 would be coupled as areceive circuit to receive the communicated signal as a current pulseI_(TR1) 160 or as a voltage pulse V_(TR1) 167.

The transmit circuits 162 and 182 in the Transceiver circuits 160 and180 could include pulse current sources 164 and 184 respectively and thereceive circuits 165 and 185 in the Transceiver circuits 160 and 180could include comparator circuits 166 and 186 with threshold voltages168 and 188 respectively.

To illustrate an example of practical application in IC industry, FIG.2A and FIG. 2B show an example integrated circuit package 210 withgalvanically isolated magnetically coupled conductive loops formed bygalvanically isolated conductors of the lead frame inside theencapsulated portion of the integrated circuit package in accordancewith the teachings of the present invention. In example illustrated inFIGS. 2A and 2B, there are external pins 201, 202, 203 and 204, as wellas external pins 205, 206, 207 and 208, on two sides of integratedcircuit package 210. In the example, all of the external pins are partof the lead frame 298 that comprises the internal conductive elements296 and 297 that are fundamentally part of integrated circuit package210 before any bond wires, such as bond wires 295, are introduced, andextend from the encapsulation 299 of integrated circuit package 210 asshown. In one example, lead frame 298 may be comprised of knownconductive materials utilized for lead frames in integrated circuitpackaging, such as for example copper, and is substantially flat andembedded in a molding compound of integrated circuit package 210. In theexample, lead frame 298 provides electrical connectivity to and fromcircuitry coupled to pins 201 to 208 of package 210 as well as providesmechanical support for the connection of bond wires 295.

FIG. 2B shows a view inside the encapsulation 299 revealing one examplestructure of the galvanically isolated magnetically coupled conductiveloops 215 and 211 formed by isolated first and second conductors 296 and297 of lead frame 298 of the example integrated circuit package 210 ofFIG. 2A in accordance with the teachings of the present invention. Inparticular, as shown in the illustrated example, lead frame 298 includesfirst conductor 297 and a second conductor 296, which are encapsulatedin insulating molding compound material within encapsulation 299. In oneexample, first and second conductors 297 and 296 of lead frame 298 maybe formed from a flat sheet of metal by etching, stamping, punching, orthe like, to form first conductive partial loop 215 in first conductor297, and a second conductive partial loop 211 in second conductor 296.In the example depicted in FIG. 2B, a bond wire 295 is coupled to secondconductor 296 as shown to couple together portions of second conductivepartial loop 211. In the depicted example, second conductor 296 isgalvanically isolated from first conductor 297. In one example, bondwire 295 has a sufficient path length to provide sufficient isolationspace from first conductor 297 in order to maintain the galvanicisolation between first conductor 297 and second conductor 296. Inanother example not illustrated, it is appreciated that one or moreadditional bond wires may be included coupling together portions offirst conductive loop 215 and/or second conductive loop 211. It isappreciated that circuit elements connected between pins 201, 202 andpins 203, 204 are needed to complete the partial conductive loop 215shown in order to transmit or receive signals through the communicationlink. Likewise it is appreciated that circuit elements connected betweenpins 205, 206 and pins 207, 208 are needed to truly complete the partialconductive loop 211 shown in order to transmit or receive signalsthrough the communication link. However for the purposes of thisdescription, partial conductive loops 211 and 215 may be referred to asconductive loops. It is appreciated that this comment also extends tothe subsequent discussion of FIG. 1C and FIG. 1D below.

As shown in the example, second conductive loop 211 is disposed withinencapsulation 299 proximate to and magnetically coupled to a firstconductive loop 215 to provide a communication link between thegalvanically isolated first conductor 297 and second conductor 296 inaccordance with the teachings of the present invention. In one example,magnetically coupled portions of the first and second conductive loops215 and 211 are substantially flat and disposed substantially in a sameplane. As shown in the illustrated example, the first and secondconductive loops 215 and 211 each consist of one turn. In one example,the communication link provided by the magnetic coupling between secondconductive loop 211 and first conductive loop 215 is utilized tocommunicate one or more signals between galvanically isolated secondconductor 296 and first conductor 297 of the lead frame 298 inaccordance with the teachings of the present invention. In one example,a transmitting signal is applied between first terminal T1 pins 205 and206, and second terminal T2 pins 207 and 208. It is sometimes desirableto have more than one external pin common to a terminal for convenienceof assembly on a circuit board.

Continuing with the illustrated example, the signal is received by firstconductive loop 215 through the magnetic coupling from second conductiveloop 211 between first terminal R1 pins 201 and 202, and second terminalR2 pins 203 and 204. In another example, it is appreciated that thesignal can also be communicated in the opposite direction to providebidirectional communications.

As shown in the example, first terminal R1 pins 201 and 202 are coupledto first conductive loop 215 through a lead frame connection 216 andsecond terminal R2 pins 203 and 204 are coupled to first conductive loop215 through a lead frame connection 218. In the example, the signals atterminals T1 and R1 are in phase in accordance with magnetic couplingand induction laws. In one example, the connections of each terminal T1214, T2 212, R1 216 and R2 218 to the respective pairs of outside pins205/206, 207/208, 201/202 and 203/204, as described above, by providingmultiple assembly options simplifies the physical connections on acircuit board on which integrated circuit package 210 is mounted.

FIG. 2C shows an outside view of one example of an integrated circuitpackage 250 with galvanically isolated magnetically coupled conductiveloops formed by isolated conductors of the lead frame 298 inside theencapsulated portion of the integrated circuit package 250 in accordancewith the teachings of the present invention. It is appreciated thatintegrated circuit package 250 of FIG. 2C shares many similarities withintegrated circuit package 210 of FIG. 2A. For instance, integratedcircuit package 250 of FIG. 2C includes an encapsulation 299 in which alead frame 298 is disposed. However, one difference is that instead ofhaving external pins arranged at two sides of the integrated circuitpackage, integrated circuit package 250 includes external pins 252, 254,256 and 258 arranged on one side of integrated circuit package 250. Inthe example, all of the external pins are part of the lead frame 298 ofintegrated circuit package 250 and extend from a single side of theencapsulation 299 of integrated circuit package 250 as shown.

FIG. 2D shows a view inside the encapsulation 299 of one examplestructure of galvanically isolated magnetically coupled conductive loops215 and 211 formed by the isolated first and second conductors 297 and296 of the lead frame 298 of the example integrated circuit package ofFIG. 2C in accordance with the teachings of the present invention. It isappreciated that the view inside the encapsulation 299 of integratedcircuit package 250 shares many similarities with the view inside theencapsulation 299 of integrated circuit package 210. For instance, asshown in FIG. 1D, lead frame 298 includes first conductor 297 and asecond conductor 296 encapsulated in insulating material withinencapsulation 299. In the depicted example, second conductor 296 isgalvanically isolated from the first conductor 297. As shown in theexample, a second conductive loop 260 of second conductor 298 isdisposed within encapsulation 298 proximate to and magnetically coupledto a first conductive loop 255 included in first conductor 297 toprovide a communication link between the galvanically isolated firstconductor 297 and second conductor 296 in accordance with the teachingsof the present invention. One difference from the example illustrated inFIG. 2B is that in the example illustrated in FIG. 2D, there is no bondwire 295 included in first conductive loop 255 and/or second conductiveloop 260.

In the example illustrated in FIG. 2D, the communication link providedby the magnetic coupling between second conductive loop 260 and firstconductive loop 255 is utilized to communicate one or more signalsbetween galvanically isolated second conductor 296 and first conductor297 of the lead frame 298 in accordance with the teachings of thepresent invention. In the example, the transmitting signal is appliedbetween first terminal T1 pin 258 and second terminal T2 pin 252. Asshown in the example, first terminal T1 pin 258 and second terminal T2252 are coupled to second conductive loop 260. The signal is received byfirst conductive loop 255 through the magnetic coupling from secondconductive loop 260 between first terminal R1 pin 256 and secondterminal R2 pin 254. In another example, it is appreciated that thesignal can also be communicated in the opposite direction to providebidirectional communications.

FIG. 3A shows an outside view of an example of an integrated circuitpackage 315 with a magnetically coupled communication link formed byisolated conductive loops of the lead frame 398 inside the encapsulation399 of the integrated circuit package 315 in accordance with theteachings of the present invention. In the example illustrated in FIG.3A, there are external pins 301, 302, 303, 304, 305, 306, 307, 309, 310,311 and 312 as shown. In the example, all of the external pins are partof the lead frame 398 of integrated circuit package 315 and extend fromthe encapsulation 399 of integrated circuit package 315 as shown. In oneexample, lead frame 398 may be comprised of known conductive materialsutilized for lead frames in integrated circuit packaging, such as forexample copper, and is substantially flat and encapsulated in a moldingcompound. In the example, lead frame 398 provides electricalconnectivity to and from internal circuitry within encapsulated portionof the integrated circuit package 315 as well as provides mechanicalsupport for integrated circuits and bond wires inside package 315.

FIG. 3B shows a view inside the encapsulation 399 revealing one examplethe structure of galvanically isolated magnetically coupled conductiveloops 337 and 335 formed by isolated first and second conductors 397 and396 of the lead frame 398 of the example multi-die isolated controllerintegrated circuit package 315 of FIG. 3A in accordance with theteachings of the present invention. In particular, as shown in theillustrated example, lead frame 398 includes first conductor 397 and asecond conductor 396 encapsulated in insulating material withinencapsulation 399. As shown in the depicted example, a first conductor397 includes a first conductive loop 337 and second conductor 396includes a second conductive loop 335. As shown in the example, secondconductive loop 335 is disposed within encapsulation 399 proximate toand magnetically coupled to a first conductive loop 337 to provide acommunication link between the galvanically isolated first conductor 397and second conductor 396 in accordance with the teachings of the presentinvention. In one example, first conductor 397 also includes an optionalthird conductive loop 338, which in one example may be utilized fornoise cancellation and is attached to tie bar 339 as shown. In oneexample, tie-bar 339 provides a mechanical support connection during themanufacture of package 315 before the lead frame 398 is encapsulatedwith encapsulation 399. In one example the encapsulation 399 isinjection molded with a molding compound. The communication linkprovided by the magnetic coupling between second conductive loop 335 andfirst conductive loop 337 is utilized to communicate one or more signalsbetween the galvanically isolated second conductor 396 and firstconductor 397 of the lead frame 398 in accordance with the teachings ofthe present invention.

In FIG. 3B the current signal from transmit circuit 367 that in oneexample is included in controller die 360, assembled on the die pad 334,is injected through the bond wire 344 from node 341 of transmit circuit367. The current signal flows to the end node 343 of the bond wire 344and then completes the second loop 335, flowing through the lead frameback to the transmit circuit 367 through the bond wire 361. The injectedsignal generates a changing magnetic field that induces a voltage signalin the first conductive loop 337 and results in a current signal closingfrom the first conductive loop 338 to the receive circuit 335 throughthe bond wires 377 and 357. The receive circuit 335 may be included inthe first controller die 355 assembled on the die pad 333 that is theprimary ground.

FIG. 3C shows another view inside the encapsulation 399 in which a firstcontrol die 350 is mounted on and coupled to the first conductor 397 anda second control die 360 is mounted on and coupled to the secondconductor 396 in accordance with the teachings of the present invention.In the illustrated example, first control die 350 is mounted on die pad333 and second control die 360 is mounted on die pad 334 as shown. Inthe illustrated example, die pads 333 and 334 are utilized as primaryand secondary ground pads, respectively. In the example shown in FIG.3C, a magnetically coupled communication link between the first controldie 350 and second control die 360 is formed by the magnetically coupledcommunication link between the first conductive loop 337 and secondconductive loop 335 in accordance with the teachings of the presentinvention. In one example, multi-die isolated controller integratedcircuit package 315 may be utilized in a switch mode power convertersuch as for example a synchronous flyback switch mode power converterwith secondary control in accordance with the teachings of the presentinvention.

Products and applications that require low output voltages, such as forexample 5V and below, in some cases, use synchronous rectification toachieve high efficiency and compact form factor. Synchronousrectification utilizes a MOSFET (metal oxide semiconductor field effecttransistor) that is switched to behave like a rectifier, in place of anoutput rectifier diode, to reduce voltage drop and power loss. Theswitching action of an output MOSFET rectifier is synchronized with themain power switch with well-controlled gating signals. In one example,first control die 350 includes a primary control circuit and a switch(in one example a MOSFET) for use in the primary side of a synchronousflyback switch mode power converter, and the second control die 369includes a secondary control circuit for use in the secondary side ofthe synchronous flyback switch mode power converter. In variousexamples, the primary control circuit and switch/MOSFET may beimplemented with a monolithic or hybrid structure for the first controldie 350.

As shown in the example illustrated in FIG. 3C, the primary switch (orMOSFET) is included in first control die 350. In one example, the drainterminal D 340 of the MOSFET is coupled through bond wires 342 to pin301. The source terminal S 345 of the MOSFET is coupled through bondwires 347 to the primary ground die pad 333, which is accessible throughsource pin 302. In the illustrated example, there is a wide clearance(i.e., missing pins) between drain pin 301 and source pin 302. In theillustrated example, the wide pad of source pin 302 is internallycoupled to a primary ground pad 333, which may also serve as a heatsink. In one example, pins 303 and 304 are coupled to first control die350 through bond wires 352 and 354, respectively, to connect the firstcontrol die 350 to external circuitry such as for example line undervoltage (example of UV 536 in FIG. 5) and supply bypass capacitor(example of BP 531 in FIG. 5).

Bond wire 336 couples the third conductive loop 338 to the first controldie 350. Due to a changing magnetic field generated by a changingcurrent flowing in second conductive loop 335, a voltage signal isinduced in the first conductive loop 337. In the example of FIG. 3Cfirst conductive loop 337 is coupled to the third conductive loop 338(the optional noise cancellation loop that is an extension of the firstconductive loop). The induced voltage signal is coupled through bondwires 336 and 347 to the receive circuit that in one example is includedin the primary die 350 on the primary ground die pad 333.

In the example, pin 305 is attached to second conductive loop 335 ofsecond conductor 396 for mechanical support. The signal communicatedfrom second control die 360 is coupled to second conductive loop 335through bond wires 344 and 361, which complete the second conductiveloop 335. As shown in the example, bond wire 344 is a connectioncoupling second conductive loop 335 at point 343 to second control die360 at point 341. Pin 312 in one example is coupled through the currentsense bond wire 371 to the secondary Ground pad 334 and the sensedvoltage drop on bond wire 371 is coupled to second control die 360through bond wires 370 and 372 and is utilized for a secondary currentmeasurement. In one example, the bond wires 362, 364, 365 and 366 arecoupled between second control die 360 and pins 306, 307, 308, 309 and310, respectively, and are utilized for the input/output of secondarysignals. In one example, pin 311 provides access to secondary ground pad334 as shown.

In one example, the slot on secondary ground pad 334 under the secondcontrol die 360 makes the second conductive loop 335 longer by forcingthe current through the second conductive loop 335 to ground pad 334 toflow closer and parallel to the first conductive loop 337 to improvemagnetic coupling. The smaller first conductive loop 337 proximate toand surrounded by the second conductive loop 335 provides a strongmagnetic coupling of first and second conductive loops in accordancewith the teachings of the present invention. In one example, lead frame398 is flat, but in other examples some portions of the lead frame 398may be up set and/or down set for optimum vertical positioning toaccommodate die thickness, optimizing bond wire profiles and to align totie bars and external pins of the integrated circuit package 315.

FIG. 3D shows an example side-view of a bond wire 336, which asmentioned above is an electrical connection, and is coupled to secondcontrol die 360 at point 341 and second conductive loop 335 at point 343of the second conductive loop 335 in accordance with the teachings ofthe present invention. As shown in the example, bond wire 336 is at ahigher level than the level of second conductive loop 335 and pin pad334 of lead frame 398. As shown, bond wire 336 has sufficient span tocomplete second conductive transmitter loop 335 and to be isolated fromthe first conductive loop 337.

FIG. 4A shows a tilted 3D (3 dimensional) view of an inside view of oneexample of a lead frame of an integrated circuit package with amagnetically coupled communication link that is formed with magneticallycoupled conductive loops of isolated conductors of the lead frame insidethe encapsulated portion of the integrated circuit package in accordancewith the teachings of the present invention. FIG. 4A shows theillustrated lead frame structure shares similarities with the lead frame398 structures of FIG. 3B and FIG. 3C. In particular, in the example ofFIG. 4A, the lead frame structure includes a first conductor including aprimary die pad 433 and a first conductive loop 437, as well as a thirdconductive loop 438, which correspond to die pad 333, first conductiveloop 337, as well as third conductive loop 338, respectively, of FIGS.3B and 3C. In addition, in the example of FIG. 4A, the lead framestructure also includes a second conductor including a secondary die pad434 and a second conductive loop 435, which correspond to die pad 334and second conductive loop 335, respectively, of FIGS. 3B and 3C. InFIGS. 4A and 4B the tie-bar connection 439A to support the thirdconductive loop 438 is at a different location than the tie-barconnection 339 to support the third conductive loop 338 in FIGS. 3B and3C and the tie-bar connection 439B of FIGS. 4A and 4B is not present inthe lead frame 398 of FIGS. 3B and 3C. Consequently, the lead framedesign shown in FIGS. 3A, 3B and 3C has no tie bar connections on thetop and bottom sides of the encapsulation increasing the externalcreepage distance between the primary and secondary conductors of thelead frame to the shortest distance between external pins 304 and 305 orbetween external pins 301 and 312, whichever is smaller, measured alongthe external surface of the encapsulation.

FIG. 4B shows a tilted 3D view of another inside the encapsulation viewof one example of a lead frame of a multi-die isolated controllerintegrated circuit package with a communication link between thecontroller dice that are formed with magnetically coupled conductiveloops of isolated conductors of the lead frame inside the encapsulatedportion of the integrated circuit package in accordance with theteachings of the present invention. FIG. 4B shows a lead frame structuresharing similarities with the lead frame structure shown in FIG. 4A. Inthe example illustrated in FIG. 4B, the primary and secondary dice areshown mounted on the lead frame. As shown in the illustrated example,the primary switch 450 and controller 451 are on different dice—which iscommonly referred to as a hybrid structure. In the example of FIG. 4B,the power MOSFET has a high power rating, which results in a separatedie 450 having a large size that covers substantially all of the primaryground die pad 433. In the illustrated example, the primary control die451 is mounted over part of the third conductive loop 438 as shown. Thesecondary control die 452 is mounted on the secondary ground die pad 434as shown.

It is appreciated that an integrated circuit package having amagnetically coupled communication link between galvanically isolatedconductors of the lead frame inside the encapsulated portion of theintegrated circuit package in accordance with the teachings of thepresent invention may be utilized in a variety of differentapplications. Although several different switch mode power convertertopologies utilizing such an integrated circuit package having amagnetically coupled communication link are described herein, it isappreciated that the specific examples described in this disclosure areprovided for explanation purposes, and that other applications mayutilize a magnetically coupled communication link between galvanicallyisolated conductors of a lead frame inside the encapsulated portion ofan integrated circuit package in accordance with the teachings of thepresent invention.

To illustrate, FIG. 5 shows one such example application with aschematic of an example synchronous flyback switch mode power converter500 with secondary control utilizing one example of a multi-die isolatedcontroller integrated circuit package 560 having a magnetically coupledcommunication link 540 between the controller dice that is formed withgalvanically isolated conductors of a lead frame inside the encapsulatedportion of the integrated circuit package 560 in accordance with theteachings of the present invention.

It is appreciated that secondary control for a flyback converter hasadvantages of tighter output regulation and faster response to loadtransients. However, as discussed previously, conventional methods ofsecondary control often use external isolation devices, such as forexample opto-couplers, which increase the complexity and cost of theswitch mode power converter. By using an example multi-die isolatedcontroller integrated circuit package 560 having a magnetically coupledcommunication link 540 with isolated primary and secondary control dice,externally added isolation components such as opto-couplers are nolonger needed in accordance with the teachings of the present invention.Furthermore, since integrated circuit package 560 provides amagnetically coupled communication link by using the lead frame of theintegrated circuit package as discussed previously, galvanic isolationis maintained between the primary and secondary sides of the switch modepower converter at nearly zero additional cost, without having to addexternal isolation components in accordance with the teachings of thepresent invention.

In the example synchronous flyback switch mode power converter 500, theprimary and secondary controllers are galvanically isolated from oneanother, but there is still reliable communication between the primaryand secondary controllers. It is appreciated that although the exampleof FIG. 5 shows a synchronous flyback converter, a standard flybackconverter, where synchronous MOSFET 550 is replaced by a diode, wouldalso benefit from the teachings of the present invention.

In the example illustrated in FIG. 5, synchronous flyback switch modepower converter 500 includes an input coupled to an ac line 505 asshown. A full-bridge rectifier 510 is coupled to ac line 505 to generaterectified ac 515, which is filtered by capacitance C_(F) 517. Therectified ac 515 is coupled to be received by energy transfer element520, which includes a primary winding 521 and a secondary winding 522 asshown. In the illustrated example, clamp circuit 525 is coupled acrossprimary winding 521 of energy transfer element 520 as shown.

In the depicted example, a switching device S1 530 is coupled to theinput of synchronous flyback switch mode power converter 500 at theprimary ground 501 and to the energy transfer element 520 at primarywinding 521. In the illustrated example, switching device S1 530 may beincluded in a monolithic or hybrid structure in the integrated circuitpackage 560. As shown in the depicted example, switching device S1 iscontrolled by control signal 539 from the primary controller die 535 andregulates the energy transfer through primary winding 521 of transformer520 to the secondary winding 522 in response to line and load changes.Clamp circuit 525, which in the illustrated example is adiode-resistor-capacitor circuit, is coupled to clamp the turn-offspikes that result from the leakage inductance from primary winding 521across the switching device S1 530.

As shown in the example of FIG. 5, switch S2 550 and anti-parallel diodeD2 555 are coupled to secondary winding 522 at the secondary side andserve as a synchronous rectifier of synchronous flyback switch modepower converter 500. In one example, the diode D2 555 is an externallyconnected Schottky diode. In one example, switch S2 550 is controlled bya signal from the SR pin of the secondary controller die 565. Wheneverthe voltage at SR terminal 575 rises to a value higher than the gatethreshold voltage, the synchronous rectifier provided by switch S2 550begins conducting current. The secondary ripple is smoothed by outputfilter capacitance C1 586 and the dc output voltage V0 580 is applied toload 585 with load current Io 582. The output voltage V0 580 is sensedthrough the resistor divider comprised of resistors 572 and 574, whichis coupled to the feedback pin FB 573 of the secondary controller. It isappreciated that in other examples resistors 574 and 572 could beintegrated within integrated circuit 560 while still benefiting from theteachings of the present invention.

At startup, primary die 535, which is referenced to the primary ground501, starts the switching of switch S1 530, which starts the transfer ofenergy to the secondary side. The bypass pin BP 531 is externallycoupled to the bypass capacitor 532. The line under voltage pin UV 536is externally coupled through resistor 537 to the ac input line, whichin another example could be coupled to a rectified ac bus 515.Communication between the primary die 535 and secondary die 565 isthrough a magnetic coupling provided by a magnetically coupledcommunication link 540 formed by isolated conductors of the lead frameof the integrated circuit package in accordance with the teachings ofthe present invention. In various examples, the communication link 540is implemented using galvanically isolated conductive loops included inthe lead frame of the integrated circuit package as described above inaccordance with the teachings of the present invention.

FIG. 6 shows a schematic of one example of a flyback switch mode powerconverter 600 utilizing one example of a multi-die isolated controllerintegrated circuit package including a bidirectional magneticallycoupled communication link between the controller dice inside theencapsulated portion of the integrated circuit package in which outputinformation is transferred to a primary side through the magneticallycoupled communication link and a line zero-cross detection signal istransferred to the secondary side through the magnetically coupledcommunication link in accordance with the teachings of the presentinvention.

In the example illustrated in FIG. 6, flyback switch mode powerconverter 600 includes an input coupled to an ac line 605 as shown. Afull-bridge rectifier 610 is coupled to ac line 605 to generaterectified ac 615, which is filtered by capacitance C_(F) 617. Therectified ac 615 is coupled to be received by energy transfer element620, which includes a primary winding 621 and a secondary winding 622 asshown. In the illustrated example, clamp circuit 625 is coupled acrossprimary winding 621 of energy transfer element 620 as shown.

In the depicted example, a switching device S1 630 is included in anintegrated circuit package 660. In one example, the switch die and theprimary control die may be structured as monolithic or hybrid dice. Inthe example, switching device S1 630 is coupled to the input of flybackswitch mode power converter 600 at the primary ground 601 and to theenergy transfer element 620 at primary winding 621. As shown in thedepicted example, switching device S1 630 is controlled by controlsignal 639 from the primary controller die 635 and regulates the energytransfer through primary winding 621 of transformer 620 to the secondarywinding 622 in response to line and load changes. Clamp circuit 625,which in the illustrated example is a diode-resistor-capacitor circuit,is coupled to clamp the turn-off spikes that result from the leakageinductance from primary winding 621 across the switching device S1 630.In the illustrated example, the secondary rectifier diode D2 655 inflyback only conducts current during an off-time of the primary switch630.

The secondary ripple is filtered by the output filter capacitance C1 686and the dc output voltage V0 680 is applied to the load 685 with loadcurrent Io 682. The output voltage V0 680 is sensed through resistordivider comprised of resistors 672 and 674, which is coupled to thefeedback pin FB 673 of the secondary controller die 665 and isreferenced to secondary ground 691 isolated from the primary ground 601.In one example, feedback signal 673 is a data signal that is transmittedthrough the magnetic coupling of the lead-frame communication loop 641and received by the primary die 635 in reference to the primary ground601. In one example, the FB signal 673, transferred by lead framemagnetic coupling of the communication link 640 to the primary sidecontroller die 635, may be either a digital or an analog signal. FBsignal is utilized in combination with the input line informationreceived at pin 634 through resistor 637 to generate gate control signal639 to control the switching of switch S1 630 to regulate the transferof energy through energy transfer element 620 to the output. In oneexample, lead frame communication link 640 includes unidirectionalcommunication links 641 and 642 to transmit one or more control signalsbetween dice 665 and 635 in accordance with the teachings of the presentinvention. In another example, lead frame communication link 640includes a single bidirectional communication link (as depicted in FIG.1B) using the same magnetically coupled lead frame loop to transmit oneor more control signals in either direction between dice 665 and 635 inaccordance with the teachings of the present invention.

In one example, the specific control function of the example flybackswitch mode power converter 600 of FIG. 6 also utilizes a zero-crosssignal of the ac line that is sensed at ac line input 605 through theshunt connected resistors 602 and 603 at the common point 604 referencedto the primary ground 601 as shown. In the example, zero sense signal606 is coupled to primary die 635 and referenced to primary ground 601,and is transmitted through the magnetic coupling of the lead-framecommunication loop 642 and received by the secondary die 665 withreference to the secondary ground 691, which could be utilized as anisolated remote control signal. For example, the zero-cross signal (apulse synchronous with the ac input voltage passing through zero atevery line cycle) could be utilized as an isolated signal for someelectric appliances, such as for example washing machines to sense linefrequency or generate timing signals necessary for an efficient loadswitching in the appliance.

As shown in the illustrated example, the lead frame communication link640 is bidirectional and includes two unidirectional communication links641 and 642. Communication link 642 is unidirectional in a reversedirection of lead frame communication link 641. It is appreciated thateven though in the illustrated example the individual lead framecommunication links are described as unidirectional communication links,in another example, a single lead frame communication link can beutilized in a bidirectional implementation (as presented, for example,in FIG. 1B) instead of two unidirectional communication links inaccordance with the teachings of the present invention.

Even though the magnetically coupled communication link built inaccordance with the teachings of this invention provides galvanicisolation, one skilled in the art would appreciate that the overallsystem, such as a switch mode power converter, that practices thisinvention need not necessarily be galvanically isolated between theinput and output of the system to benefit from the advantages of thisinvention. For example, in non-isolated converters, a galvanicallyisolated communication link in accordance with the teachings of thepresent invention allows communication between two parts of a switchmode power converter that are referenced to different voltages whichcould be fixed or changing relative to each other over time.

FIG. 7 shows a schematic of one example of a buck converter 700utilizing one example of a multi-die isolated controller integratedcircuit package with a magnetically coupled communication link formed byisolated conductors of the lead frame inside the encapsulated portion ofthe integrated circuit package in accordance with the teachings of thepresent invention.

In the example illustrated in FIG. 7, buck converter 700 includes aninput coupled to an ac line 705 as shown. A full-bridge rectifier 710 iscoupled to ac line 705 to generate rectified ac 715, which is filteredby capacitance C_(F) 717. The ac line 705 is rectified through bridgerectifier 710 and the rectified AC 715 is filtered by the capacitanceC_(F) 717 and applied to a high-side switch depicted as an N-channelMOSFET switch S1 720. In the example, MOSFET switch S1 720 is turned onby applying control signal 725. In particular, when the gate to sourcevoltage across the gate resistor 723 rises above the gate thresholdvoltage, MOSFET S1 720 is turned on.

An energy transfer element 740, which in the illustrated example is aninductor 740, is coupled to MOSFET switch S1 720 as shown. In operation,energy is transferred to the inductor 740 of the buck converter 700through the switching control of MOSFET switch S1 720. In particular,when MOSFET switch S1 720 is on, energy is transferred to the inductor740 and during an off time of the MOSFET switch S1 720, the energystored in the inductor 740 is delivered to the load 765 by circulatingthe load current 763 through the load 765 and circulating diode 745. Theregulated output voltage V0 760 is filtered by capacitance C1 761.

In the illustrated example, the switching control signal 725 for thehigh-side MOSFET switch S1 720 in a non-isolated buck converter isisolated from the converter reference ground 701. Feedback signal FB 755is generated from output voltage V0 760 through a resistive dividerincluding resistors 752 and 754, and is input to the controller die 736,which is referenced to the converter ground 701. In the illustratedexample, the incoming/outgoing control signals 702 are coupled to thecontroller die 736. In one example, the incoming/outgoing controlsignals 702 may include for example an incoming switching signal andoutgoing status/fault protection signals, and are referenced to theconverter ground 701. In the example, the control signals 702 arecommunicated between the isolated high-side control die 732 andcontroller die 736 through a bidirectional communication link providedby the magnetic coupling of first and second conductive loops of thelead frame inside the integrated circuit package in accordance with theteachings of the present invention. In one example, the supply voltageto the lower control die 736 is V_(L) 738, which is referenced toconverter ground 701, and the supply voltage to the high side controldie 732 is V_(H) 739, which is referenced to the source of MOSFET switchS1 720.

It is appreciated that in other examples, synchronous buck convertersmay be implemented with the circulating diode 745 being replaced by acontrolled switch with reverse current conduction. Switching in thatexample of the controlled switch is synchronized with the high-side buckmain MOSFET switch S1 720. It is appreciated that the controller circuitfor a synchronous buck converter can also benefit in the same way asother examples from a magnetically coupled communication link throughgalvanically isolated first and second conductive loops of the leadframe in accordance with the teachings of the present invention. Inaddition, it is noted that another example schematic of a synchronousconverter could utilize a half-bridge configuration.

FIGS. 8A, 7B and 8C introduce integrated circuit package examples havingisolated control circuits utilizing magnetically coupled first andsecond conductive loops of a lead frame in an integrated circuit packageto provide communication links in various half-bridge configurations inaccordance with the teachings of the present invention. For instance,FIG. 8A shows a schematic of an example of a switch mode power converter800 including one example of a half-bridge configuration 850 that may beincluded in an example of a multi-die isolated controller integratedcircuit package with a magnetically coupled communication link that isformed by isolated conductors of the lead frame inside the encapsulatedportion of the integrated circuit package in accordance with theteachings of the present invention. As shown, an input stage 810provides a dc voltage to half-bridge configuration 850 at inputterminals of an input port 820 of half-bridge configuration 850. In oneexample, half-bridge configuration 850 generates high frequency pulsesat output terminals of an output port 825 of half-bridge configuration850, which are coupled to drive an energy transfer element in an outputstage 730 of the switch mode power converter 800.

In the illustrated example, half-bridge configuration 850 includes aswitching leg coupled to the input port 820 and output port 825. Theswitching leg includes a high-side switch Q2 857 and a low-side switchQ1 853 that are coupled to drive the energy transfer element in outputstage 830 as shown. A plurality of control circuits are coupled tocontrol switching of the high-side switch Q2 857 and low-side switch Q1853. In the illustrated example, one of the plurality of controlcircuits is high-side controller 855, which is coupled to controlhigh-side switch Q2 857 with a control signal 856 that is referenced tothe source of high-side switch Q2 857, which is connected to half-bridgemid-point A 823 and to the high potential terminal #1 of the half-bridgeoutput port 825 as shown. Another one of the plurality of controlcircuits is low-side controller 851, which is coupled to controllow-side switch Q1 853 with a control signal 852 that is referenced tothe source of low-side switch Q1 853 and ground reference 801.Accordingly, in one example, high-side controller 755 and low-sidecontroller 851 are galvanically isolated from one another. As shown inthe depicted example, there is a magnetically coupled communication link860 between isolated high-side controller 855 and low side controller851 through which one or more control signals may be communicated.

In one example, the isolated low-side controller 851 and the high-sidecontroller 855 dice are included in a single integrated circuit packagein which communication link 860 is included in the integrated circuitpackage with a magnetically coupled communication link formed bygalvanically isolated conductors of the lead frame inside theencapsulated portion of the integrated circuit package in accordancewith the teachings of the present invention. In one example,communication link 860 is a bidirectional link between respectivetransceiver circuits of the galvanically isolated low-side controller851 and the high-side controller 855 dice. In another example,communication link 860 includes a plurality of unidirectional linksbetween respective transmit circuits and receive circuits of thegalvanically isolated low-side controller 851 and the high-sidecontroller 855 dice. In one example, the control signals 852 and 856 ofthe low-side and high-side switching devices 853 and 857, respectively,are synchronized tightly to avoid any overlapped switching of high-sideand low-side switches 853 and 857 that could result in shoot throughbetween the input port 820 terminals.

In one example, low side controller 851 is coupled to receive inputcontrol signals 802 as shown. In one example, the control signals 852and 856 are coupled to drive the low-side and high-side switchingdevices 853 and 857 in response to the input control signal 802. In oneexample, low-side controller 851 is further coupled to output a statussignal 804, which in one example may include fault/status informationand may be used to protect the half-bridge converter in the case offault conditions. In one example, the status signal 804 may includefault/status information regarding the switch Q1 873 from the low-sidecontroller 851 as well as fault/status information regarding the switchQ2 877 from the high-side controller 855 received by low-side controller851 through communication link 860.

In one example, supply V_(L) 885 is coupled to the low-side controller851 and is referenced to ground reference 801. Supply V_(H) 889 iscoupled to the high-side controller 855 and is referenced to half-bridgemidpoint A 823. One example of a high-side supply through a bootstrapcapacitor is depicted below in FIG. 8C. In other examples, the high-sidesupply could be provided by a galvanically isolated winding on atransformer or the high-side supply could be supplied from the drain ofthe high-side switch.

FIG. 8B shows a schematic of another example of a switch mode powerconverter 803 including one example of a half-bridge configuration 870that may be included in an example of a multi-die isolated controllerintegrated circuit package with a magnetically coupled communicationlink formed by isolated conductors of the lead frame inside theencapsulated portion of the integrated circuit package in accordancewith the teachings of the present invention. It is appreciated thatswitch mode power converter 803 of FIG. 8B shares many similarities withswitch mode power converter 800 of FIG. 8A. For instance, switch modepower converter 803 of FIG. 8B includes an input stage 810 that providesa dc voltage to half-bridge configuration 870 at input terminals of aninput port 820 of half-bridge configuration 870. In one example,half-bridge configuration 870 generates high frequency pulses at outputterminals of an output port 825 of half-bridge configuration 870, whichare coupled to drive an energy transfer element in an output stage 830of the switch mode power converter 803.

In addition, half-bridge configuration 870 includes a switching legcoupled to the input port 820 and output port 825. The switching legincludes a high-side switch Q2 877 and a low-side switch Q1 875 that arecoupled to drive the energy transfer element in output stage 830 asshown. A plurality of control circuits is coupled to control switchingof the high-side switch Q2 877 and low-side switch Q1 875. In theillustrated example, one of the plurality of control circuits ishigh-side controller 875, which is coupled to control high-side switchQ2 877. Another one of the plurality of control circuits is low-sidecontroller 871, which is coupled to control low-side switch Q1 875.

One difference between switch mode power converter 803 of FIG. 8B andswitch mode power converter 800 of FIG. 8A is that in the example switchmode power converter 803 of FIG. 8B, the low-side and high-sideswitching devices, which are depicted as IGBTs (insulated gate bipolartransistors) Q1 875 and Q2 877 with drivers 872 and 876, are notincluded in the controller integrated circuit package 885 of thelow-side and high-side controllers 871 and 875. In one example, theconfiguration of switch mode power converter 803 of FIG. 8B is moresuited for high voltage high power half-bridge applications. Inapplications in which IGBT switches are used and a reverse currentconduction by the switches is required, such as the depicted exampleswitch mode power converter 803 of FIG. 8B, the switches Q1 875 and Q2877 should include internal or external anti-parallel diodes depicted bydiode 879 across IGBT Q1 875 and anti-parallel diode 878 across IGBT Q2877.

In one example, high-side controller 875 and low-side controller 871 aregalvanically isolated from one another. In particular, the low-sidecontroller supply V_(L) 883 is referenced to ground reference 801 andthe high-side controller supply V_(H) 889 is isolated from the low-sidecontroller supply V_(L) 883 and referenced to the half-bridge midpoint A823. The input control signals 802 for driving half-bridge switches arecoupled to the low-side controller that controls both the high-side andthe low-side switching. As shown in the depicted example, there is acommunication link 880 between isolated high-side controller 875 and lowside controller 871 through which one or more control signals may becommunicated. In one example, the isolated low-side controller die 871and the high-side controller die 875 are included in a single integratedcircuit package in which communication link 860 is included in theintegrated circuit package with a magnetically coupled communicationlink formed by isolated conductors of the lead frame inside theencapsulated portion of the integrated circuit package 885 in accordancewith the teachings of the present invention. In one example,communication link 880 is a bidirectional link between respectivetransceiver circuits of the galvanically isolated low-side controllerdie 871 and the high-side controller die 875. In another example,communication link 880 includes a plurality of unidirectional linksbetween respective transmit circuits and receive circuits of thegalvanically isolated low-side controller die 871 and the high-sidecontroller die 875.

In one example, low-side controller 871 is further coupled to output astatus signal 804, which in one example may include fault/statusinformation and may be used to protect the half-bridge converter in thecase of fault conditions. In one example, the status signal 804 mayinclude fault/status information regarding the switch Q1 873 from thelow-side controller 871 as well as fault/status information regardingthe switch Q2 877 from the high-side controller 875 received by low-sidecontroller 871 through communication link 880.

FIG. 8C shows an example of a switch mode power converter 805, whichshares many similarities with switch mode power converter 803 of FIG.8B. In particular, all of the components of the front-stage 810, outputstage 830, half-bridge configuration 870 and the integrated circuitpackage 885 of switch mode power converter 803 of FIG. 8B are alsoincluded in switch mode power converter 805 of FIG. 8C. In the exampledepicted in FIG. 8C, a bootstrap capacitor is also included to providethe high-side controller 875 supply voltage V_(H) 889 through thebootstrap capacitor 888, which is isolated from the low side controllersupply and the low-side ground reference 801. In one example, bootstrapcapacitor 888 is charged from the low-side controller supply 882 coupledto the low-side controller supply terminal V_(L) 883 as shown. In everyswitching cycle when low-side switch Q1 875 is closed and high-sideswitch Q2 877 is open, the bootstrap capacitor 888 is charged throughdiode 886 and resistor 884 from the supply 882 with respect to groundreference 801. In addition, bootstrap capacitor 888 is coupled to supplyV_(H) 889 to the high-side controller 875 when low-side switch Q1 875 isopen, high-side switch Q2 877 is closed, and high voltage is applied tothe midpoint A 823.

It is appreciated that in another example, an isolated supply voltagemay also be provided to the high-side controller through an isolatedbias or supply winding from a transformer. In yet another example,voltage may be supplied to the high-side controller from the drainterminal of the high side switch.

FIG. 9A shows a schematic of an example of a switch mode power converter900 including one example of a full-bridge configuration 950 utilizingan example of four bidirectional magnetically coupled communicationlinks formed by isolated conductors of the lead frame inside theencapsulated portion of the integrated circuit package in accordancewith the teachings of the present invention. In one example, full-bridgeconfiguration 950 may be included in an example of a multi-die isolatedcontroller integrated circuit package with a magnetically coupledcommunication link formed by isolated conductors of the lead frameinside the encapsulated portion of the integrated circuit package inaccordance with the teachings of the present invention. As shown, aninput stage 910 provides a dc or low frequency voltage to full-bridgeconfiguration 950 at input terminals of an input port 920 of full-bridgeconfiguration 950. In one example, full-bridge configuration 950generates high frequency pulses at output terminals of an output port925 of full-bridge configuration 950, which are coupled to drive anenergy transfer element in an output stage 930 of the switch mode powerconverter 900.

In the illustrated example, full-bridge configuration 950 includes firstand second switching legs coupled to input port 920 and output port 925.As shown in the depicted example, one of the switching legs includes alow-side switch Q1 951 coupled to a high-side switch Q2 952. The otherswitching leg includes a low-side switch Q3 953 coupled to a high-sideswitch Q4 954. The first and second switching legs are coupled to drivethe energy transfer element in output stage 930 in response torespective control signals that are coupled to be received from arespective one of a plurality of control circuit dice. In theillustrated example, control circuit die 931 is coupled to generate acontrol signal 915 to control switching of low-side switch Q1 951.Control circuit die 932 is coupled to generate a control signal 916 tocontrol switching of high-side switch Q2 952. Control circuit die 941 iscoupled to generate a control signal 917 to control switching oflow-side switch Q3 953. Control circuit die 942 is coupled to generate acontrol signal 918 to control switching of high-side switch Q4 954.

In the example, control signals 915 and 917 generated from controlcircuit dice 931 and 941, respectively, are referenced to groundreference 901. Control signals 916 and 918 generated from controlcircuit dice 932 and 942, respectively, are referenced to the source ofthe high-side switches Q2 952 and Q4 954, respectively, or in otherwords are referenced to the half-bridge mid-points A 921 and B 923,respectively).

In the example depicted in FIG. 9A, full-bridge configuration 950 isimplemented with a full-bridge controller 955 in an integrated circuitpackage. In one example, the integrated circuit package may includeisolated multiple controller dice for the high-side and low-sideswitches as well as the drivers and switching devices.

In the example illustrated in FIG. 9A, the input signals 902 and thestatus signals 904 to and from the full-bridge controller 955 correspondto the operational parameters and fault/status conditions of the switchmode power converter 900. As shown in the example of FIG. 9A, one ormore control signals may be communicated between transceiver circuitry935 of full-bridge controller 955 and control circuit die 931 throughcommunication link 933. One or more control signals may be communicatedbetween transceiver circuitry 936 of full-bridge controller 955 andcontrol circuit die 932 through communication link 934. One or morecontrol signals may be communicated between transceiver circuitry 945 offull-bridge controller 955 and control circuit die 941 throughcommunication link 943. One or more control signals may be communicatedbetween transceiver circuitry 946 of full-bridge controller 955 andcontrol circuit die 942 through communication link 944. In one example,communication links 933, 934, 943 and 944 are implemented using amagnetic coupling of isolated conductive loops formed using the leadframe and bond wires of the integrated circuit package in accordancewith the teachings of the present invention. In one example thecommunication links 933, 934, 943 and 944 are bidirectional. In anotherexample, communication links 933, 934, 943 and 944 may contain aplurality of unidirectional links to provide bidirectionalcommunications.

FIG. 9B shows a schematic of an example of a switch mode power converter903 including another example of a full-bridge configuration 970utilizing an example magnetically coupled communication link formed byisolated conductors of the lead frame inside the encapsulated portion ofthe integrated circuit package in accordance with the teachings of thepresent invention. It is appreciated that switch mode power converter903 of FIG. 9B shares many similarities with switch mode power converter900 of FIG. 9A. For instance, switch mode power converter 903 of FIG. 9Bincludes an input stage 910 that provides a dc or low frequency voltageto full-bridge configuration 970 at input terminals of an input port 920of full-bridge configuration 970. In one example, full-bridgeconfiguration 970 generates high frequency pulses at output terminals ofan output port 925 of full-bridge configuration 970, which are coupledto drive an energy transfer element in an output stage 930 of the switchmode power converter 903.

In addition, full-bridge configuration 970 includes first and secondswitching legs coupled to input port 920 and output port 925. As shownin the depicted example, one of the switching legs includes a low-sideswitch Q1 951 coupled to a high-side switch Q2 952. The other switchingleg includes a low-side switch Q3 953 coupled to a high-side switch Q4954. The first and second switching legs are coupled to drive the energytransfer element in output stage 930 in response to respective controlsignals that are coupled to be received from a microcontroller 995 ofthe full-bridge configuration 970.

In the depicted example, a microcontroller 995 is programmed with aswitching program to control the full-bridge configuration 970 tocontrol the switching of switches Q1 951, Q2 952, Q3 953, and Q4 954. Inone example, the incoming switching signals 902 and the outgoing statussignals 904 to and from the microcontroller 995 correspond to theoperational parameters and fault/status conditions of the switch modepower converter 903. In one example, microcontroller 995 generatescontrol signals 991, 992, 993 and 994 in response to the input signals902. In one example, control signal 991 is communicated through a module979, which outputs a control signal 955 coupled to control the switchingof low side switch Q1 951. Control signal 992 is communicated through amodule 980, which outputs a control signal 956 coupled to control theswitching of high side switch Q2 952. Control signal 993 is communicatedthrough a module 989, which outputs a control signal 957 coupled tocontrol the switching of low side switch Q3 953. Control signal 994 iscommunicated through a module 990, which outputs a control signal 958coupled to control the switching of high side switch Q4 954.

In example illustrated in FIG. 9B, it is noted that each module 979,980, 989 and 990 includes an integrated circuit package 973, 974, 983and 984, respectively. In one example, integrated circuit packages 973,974, 983 and 984 share substantial similarities with the integratedcircuit package 210 and/or integrated circuit package 250 as describedabove with respect to FIGS. 2A, 2B, 2C and 2D. Accordingly, eachintegrated circuit package 979, 974, 975 and 976 includes galvanicallyisolated magnetically coupled conductive loops formed by isolatedconductors of the lead frame inside the respective encapsulated portionof the integrated circuit package in accordance with the teachings ofthe present invention. Therefore, the transceiver circuits ortransmit/receive circuits coupled on opposite ends of each integratedcircuit package 979, 974, 975 and 976 are galvanically isolated, but arestill able to communicate in accordance with the teachings of thepresent invention. It is appreciated that each transceiver circuitryand/or the transmit/receive circuitry included in each module 979, 980,989 and 990 can be referenced to the source terminal of controlledswitch regardless of microcontroller 995 ground reference.

In one example, each of the modules 979, 980, 989 and 990 aresubstantially similar to each other and each includes similarcomponents. To illustrate with reference to the specific example ofmodule 979, transceiver circuits 971 and 975 of module 979 communicatethrough integrated circuit package 973 as shown. In one example, adriver 977 for boosting the signal to drive the low side switch Q1 951can also be included in the module 979. In one example, the utilizationof the individual modules 979, 980, 989 and 990 is well suited for thehigh power rating full-bridge converter designs.

In one example, each of the modules 979, 980, 989 and 990 is anintegrated circuit package that contains the dice for thetransmit/receive circuitry, optional driver and a galvanically isolatedcommunication link formed by isolated conductors of the lead frameinside the encapsulated portion of the integrated circuit package inaccordance with the teachings of the present invention.

For the purposes of this disclosure, an “encapsulation” of an integratedcircuit package may be considered to be any external body, encasing ormolding that surrounds or encloses a portion of the lead frame which mayinclude one or more integrated circuit dice disposed therein, as well asconnections from the integrated circuit die pads to the lead frame andpins of the integrated circuit package. An example encapsulation may bemade from molded non-ferrous insulating material, plastic, ceramiccovers or the like. In some examples, the encapsulation of theintegrated circuit package may or may not provide hermetic sealing toprotect the items encased therein from external elements.

For the purposes of this disclosure, the term “integrated circuitpackage” refers to the type of packages used generally for integratedcircuits. It is appreciated that some embodiments of this invention mayhave no integrated circuits in the package such as the examples in FIGS.2A, 2B, 2C and 2D.

The above description of illustrated examples of the present invention,including what is described in the Abstract, are not intended to beexhaustive or to be limitation to the precise forms disclosed. Whilespecific embodiments of, and examples for, the invention are describedherein for illustrative purposes, various equivalent modifications arepossible without departing from the broader spirit and scope of thepresent invention. Indeed, it is appreciated that the specific examplevoltages, currents, frequencies, power range values, times, etc., areprovided for explanation purposes and that other values may also beemployed in other embodiments and examples in accordance with theteachings of the present invention.

What is claimed is:
 1. An integrated circuit package for use in a switchmode power converter, comprising: an encapsulation; a lead frame, aportion of the lead frame disposed within the encapsulation, the leadframe including a first conductor having a first conductive loopdisposed substantially within the encapsulation, wherein the lead framefurther includes a second conductor galvanically isolated from the firstconductor, wherein the second conductor includes a second conductiveloop disposed substantially within the encapsulation proximate to andmagnetically coupled to the first conductive loop to provide acommunication link between the first and second conductors; a firstcontrol die including a first control circuit coupled to the firstconductor; and a second control die including a second control circuitcoupled to the second conductor, wherein one or more control signals arecommunicated between the first and second control dice through thecommunication link.
 2. The integrated circuit package of claim 1,wherein the switch mode power converter comprises a switching circuitcoupled between an input of the power supply and an input of an energytransfer element, the output of the energy transfer element coupled toan output of the switch mode power converter, wherein the first controlcircuit coupled to the switching circuit to control switching of theswitching circuit in response to the one or more control signalscommunicated between the first and second control dice through thecommunication link to regulate the transfer of energy from the input ofthe switch mode power converter to the output of the switch mode powerconverter.
 3. The integrated circuit package of claim 2 wherein theswitch mode power converter comprises an isolated synchronous flybackconverter, and wherein the switch mode power converter furthercomprises: a second switch coupled to an output of the energy transferelement and the output of the switch mode power converter; and thesecond control circuit coupled to receive a feedback signalrepresentative of the output of the switch mode power converter, whereinthe second control circuit is further coupled to the second switch tocontrol switching of the second switch to transfer energy from theenergy transfer element to the output of the switch mode powerconverter, wherein the second control circuit transmits the one or morecontrol signals through the communication link to the first controlcircuit to regulate the transfer of energy from the input of the switchmode power converter to the output of the switch mode power converter.4. The integrated circuit package of claim 2 wherein the switch modepower converter comprises an isolated flyback converter, and wherein thesecond control circuit is coupled to receive a feedback signalrepresentative of the output of the switch mode power converter, whereinthe one or more control signals is responsive to the feedback signal,and wherein the second control circuit transmits the one or more controlsignals through the communication link to the first control circuit toregulate the transfer of energy from the input of the switch mode powerconverter to the output of the switch mode power converter.
 5. Theintegrated circuit package of claim 4 wherein the second control circuitis further coupled to receive an AC line zero-crossing signal from thefirst control circuit through the communication link between the firstand second control dice.
 6. The integrated circuit package of claim 2wherein the switch mode power converter comprises a buck converter,wherein the first control circuit is a high-side control circuit, andwherein the second control circuit is coupled to receive a feedbacksignal representative of the output of the switch mode power converter,wherein the one or more control signals are responsive to the feedbacksignal, wherein the second control circuit is coupled to transmit theone or more control signals through the communication link to thehigh-side control circuit.
 7. The integrated circuit package of claim 2wherein the switch mode power converter comprises a half-bridgeconverter that includes a switching leg having a high-side switch and alow-side switch coupled to drive the energy transfer element, whereinthe first control circuit is one of a plurality of control circuits,wherein each one of the plurality of control circuits is coupled tocontrol switching of a respective one of the high-side and low-sideswitches.
 8. The integrated circuit package of claim 7 wherein a statussignal is communicated from the first control circuit to an other one ofthe plurality of control circuits through the communication link.
 9. Theintegrated circuit package of claim 2 wherein the switch mode powerconverter comprises a full-bridge converter that includes first andsecond switching legs, wherein each one of the first and secondswitching legs comprises a high-side switch and a low-side switchcoupled to drive the energy transfer element, wherein the first controlcircuit is one of a plurality of control circuits, wherein each one ofthe plurality of control circuits is coupled to control switching of arespective one of the high-side and low-side switches.
 10. Theintegrated circuit package of claim 9 wherein a status signal iscommunicated from the control circuit to a full-bridge controllercircuit through the communication link.
 11. The integrated circuitpackage of claim 2 wherein the first control die is mounted on the firstconductor of the lead frame, wherein the first control die is coupled toand completes the first conductive loop.
 12. The integrated circuitpackage of claim 11 further comprising a first bond wire coupled to thefirst conductor and the first control die, wherein the first bond wireis included as a portion of the first conductive loop.
 13. Theintegrated circuit package of claim 11 wherein the second control die ismounted on the second conductor of the lead frame, wherein the secondcontrol die is coupled to the second conductive loop.
 14. The integratedcircuit package of claim 13 further comprising a second bond wirecoupled to the second conductor and the second control die, wherein thesecond bond wire is included as a portion of the second conductive loop.15. The integrated circuit package of claim 1 wherein the one or morecontrol signals comprise a coded signal.
 16. The integrated circuitpackage of claim 1 wherein the communication link comprises aunidirectional communication link.
 17. The integrated circuit package ofclaim 1 wherein the communication link comprises a bidirectionalcommunication link.
 18. A switch mode power converter, comprising: aswitching circuit coupled to an input of an energy transfer element andan input of the switch mode power converter; the energy transfer elementcoupled between the switching circuit and an output of the switch modepower converter; a control circuit coupled to the switching circuit tocontrol switching of the switching circuit to regulate a transfer ofenergy from the input of the switch mode power converter to the outputof the switch mode power converter; a first conductor including a firstconductive loop coupled to the control circuit, wherein the firstconductor is included in a lead frame of an integrated circuit package;and a second conductor included in the lead frame of the integratedcircuit package and galvanically isolated from the first conductor,wherein the second conductor includes a second conductive loop disposedproximate to and magnetically coupled to the first conductive loop toprovide a communication link between the first and second conductors,wherein the control circuit is coupled to switch the switching circuitin response to one or more control signals received from the secondconductive loop through the magnetic coupling between the first andsecond conductive loops.
 19. The switch mode power converter of claim 18wherein the switch mode power converter comprises an isolatedsynchronous flyback converter, wherein the control circuit is a primarycontrol circuit, and wherein the switch mode power converter furthercomprises: a second switch coupled to an output of the energy transferelement and the output of the switch mode power converter; and asecondary control circuit coupled to receive a feedback signalrepresentative of the output of the switch mode power converter, whereinthe secondary control circuit is further coupled to the second switch tocontrol switching of the second switch to transfer energy from theenergy transfer element to the output of the power supply, wherein thesecondary control circuit is coupled to the second conductor to transmitthe one or more control signals in response to the feedback signal,through the magnetic coupling between the first and second conductiveloops to the primary control circuit.
 20. The switch mode powerconverter of claim 18 wherein the switch mode power converter comprisesan isolated flyback converter, wherein the control circuit is a primarycontrol circuit, and wherein the switch mode power converter furthercomprises a secondary control circuit coupled to receive a feedbacksignal representative of the output of the switch mode power converter,wherein the one or more control signals is responsive to the feedbacksignal, and wherein the secondary control circuit is coupled to thesecond conductor to transmit the one or more control signals through themagnetic coupling between the first and second conductive loops to theprimary control circuit.
 21. The switch mode power converter of claim 20wherein the secondary control circuit is further coupled to receive azero crossing signal from the primary control circuit through thecommunication link between the first and second conductors.
 22. Theswitch mode power converter of claim 18 wherein the switch mode powerconverter comprises a buck converter, wherein the control circuit is ahigh-side control circuit, and wherein the switch mode power converterfurther comprises a second control circuit coupled to receive a feedbacksignal representative of the output of the switch mode power converter,wherein the one or more control signals are responsive to the feedbacksignal, wherein the second control circuit is coupled to the secondconductor to transmit the one or more control signals through themagnetic coupling between the first and second conductive loops to thehigh-side control circuit.
 23. The switch mode power converter of claim18 wherein the switching circuit comprises a half-bridge converter thatincludes a switching leg having a high-side switch and a low-side switchcoupled to drive the energy transfer element, wherein the controlcircuit is one of a plurality of control circuits, wherein each one ofthe plurality of control circuits is coupled to control switching of arespective one of the high-side and low-side switches.
 24. The switchmode power converter of claim 23 wherein a status signal is communicatedfrom the control circuit to an other one of the plurality of controlcircuits through the communication link.
 25. The switch mode powerconverter of claim 18 wherein the switching circuit comprises afull-bridge configuration that includes first and second switching legs,wherein each one of the first and second switching legs comprises ahigh-side switch and a low-side switch coupled to drive the energytransfer element, wherein the control circuit is one of a plurality ofcontrol circuits, wherein each one of the plurality of control circuitsis coupled to control switching of a respective one of the high-side andlow-side switches.
 26. The switch mode power converter of claim 25wherein a status signal is communicated from the control circuit to afull-bridge controller circuit through the communication link.
 27. Theswitch mode power converter of claim 18 wherein the control circuit isincluded in a first integrated circuit die mounted on the firstconductor of lead frame, wherein the first integrated circuit diecouples together portions of the first conductive loop.
 28. The switchmode power converter of claim 27 further comprising a first bond wirecoupled to the first conductor and the first integrated circuit die,wherein the first bond wire is included as a portion of the firstconductive loop.
 29. The switch mode power converter of claim 27 furthercomprising a second integrated circuit die isolated from the firstintegrated circuit die and mounted on the second conductor of the leadframe, wherein the second integrated circuit die couples togetherportions of the second conductive loop.
 30. The switch mode powerconverter of claim 29 further comprising a second bond wire coupled tothe second conductor and the second integrated circuit die, wherein thesecond bond wire is included as a portion of the second conductive loop.31. The switch mode power converter of claim 18 wherein the first andsecond conductive loops are coupled to respective external pin pads ofthe integrated circuit package.
 32. The switch mode power converter ofclaim 18 wherein the one or more control signals comprises a codedsignal.
 33. The switch mode power converter of claim 18 wherein thecommunication link comprises a unidirectional communication link. 34.The switch mode power converter of claim 18 wherein the communicationlink comprises a bidirectional communication link.